Process for the recovery of hydrogen which has been enriched in deuterium



March 1, 1960 E. w. A. BECKER PRocEss FOR THE RECOVERY oF HYDEoGEN WHICHHAS BEEN ENRICHED IN DEUTERIUM Filed April 29, 1957 M Mw RT W www lllgssJ J J E W o m m W www A N n WWW w. /W, mf O E g a a L fm 4 W N E 1 Lfiwlf ||||1 Aw, Nwl Il iAlfm 6 Y v b B even further.

United States ,Patenti Ofice The present invention relates toimprovements in a method of recovering waterl or hydrogen enriched indeuterium, such as is described in my earlier application,

VSerial No. 531,980, led 4September 1, 1956, which involves an exchangeof deuterium between water and hydrogen' in the presence of a catalyst.

According to one embodiment of the processidisclosed in applicationSerial `No..`531,980, natur/al hydrogen with the normal deuteriumcontent is enriched in deu` terium corresponding 4to the partitioncoeicient K2 of: `deuterium between waterand hydrogen in a hot exchangecolumn maintained at a higher temperature Tzm, Thereafter, a smallportion of thishydrogenris branched oi and is further workedup inasystem of fhot and cold columns, while the main portion of such"hydrogen is passed through a cold hcolumn maintained at alowertemperature T1 countercurren-t to water which is passed in a closedcycle through both columns to give up deuterium to the watercorresponding to the partition, coeicient K1. Expediently, the portionof the hydrogen which was branched otitis also" passed through the coldcolumn after a portion of the deuterium had been extracted therefrom solas to lower its deuterium content further.

Deuterium is only con-tained in natural hydrogen in a proportion of1:7000. In the process `disclosed in application Serial No. 531,980, yadeuterium yield of only 20 to 30% could be attained when economy ofoperation is taken into consideration. Consequently, for operation upona technical scale, very large quantities of fresh hydrogen are required.

According to the invention it was unexpectedly found that the yield ofdeuterium could be increased substantially if the hydrogen which" hasbeen depleted in deuterium during passage through the cold column of thehotcold concentrating system of the process described above is passedthrough a second cold so.called stripping column where its -deuteriurncontent is decreased A portion of the resulting hydrogen of very lowdeuterium content is drawn oft and used for chemical purposes, whereasthe remainder is brought up substantially to the original deuteriumcontent in a hot column which is associated with the cold strippingcolumn. This hydrogen is then recycled to the hot column of theconcentrating system according to application Serial No. 531,980 andworked up further 'therein'` Yhydrogen is supplied continuously at thefoot of the hot column of the concentrating system.

The accompanying (drawing diagrammatically shows an. apparatus systemfor carrying out the process according to the invention.

With reference to the drawing, natural hydrogem such as, for example, iscustomarily employed in hydrogenation plants, is supplied at 1 to thebottom of hot" column 7 and passed counter'curr'ently therein to waterenriched in deuterium whereby the exchange equilibrium` is established.The hydrogen leaving at 2 is enriched in deuterium. A portion thereof(about 1/3) is withdrawn atf2`a and passed through a second hot-coldsystem `in which a fraction thereof is further enriched in deuterium.

The hydrogen poorl in deuterium resulting from the second hot-coldsystem is mixed at 2b with. thegremaining two-thirds of the hydrogenleaving hot column 7 and v passed into -cold column 8` at 2c. In column8`, equilib rium is established with the deuterium poor water whichcorresponds to the lower temperaurefat which such column operates; thatis a portion, of Mthe deuterium migrates `out `of the hydrogen into thewater. The deuterium transfer from the cold to the hot column of theconcentrating systerntherefore is effected bythe Water cycle 11. Thehydrogen gas leaving column 8 at 3 contains about 20 to 30% lessdeuterium' than natural` hydrogen. Accordingto the invention, thishydrogen is further depleted in deuterium by passage through a coldstripping column 9 and then divided into two streams,

to that of natura hydrogen and this resulting hydrogen is then added at6 to the fresh hydrogen which is suppliedvto column 7 at 1. l

It is particularly expedient, as indicated by the interrupted` lines 13to combine water cycle 12 with water cycle 11 to one closed water cyclewhich flows ,counter-v current to the hydrogen. y u A Furtheradvantagesare attained by providing for heat exchangebetween thequantities of liquid or, respectively,..of gas which are 'at differenttemperatures, `preferably of the same phase. For exam-ple, about of theenergy which would be required when` operating without heat exchangecanbe savedby heat exchange between the water leaving the hot column 10of the stripping system and that leaving cold column 8 of theconcentrating system in order to raise the temperature of the Waterleaving column 8 to the temperature required for hot column 9.

Thepcatalyst required for acceleration of the exchange reaction can beemployed in any desired form. However, especially good results areattained when the catalyst water phase. nFor example, the liquid waterphase can be a 1 to 3% platinum sol or such phase can be a dispersion of20 g. activated carbon powder containing 10% Pt per g. of water. v

Preferably, the hot and the cold columns of the concentrating 'andstripping systems are respectively main tained at the same temperatureand pressure. For ex` ample, the cold columns can be maintained at atemperature below 100 C., preferably between 20 and 50 C., and the hotcolumn at a temperature above C., preferably about 200 C. The pressuresemployed should be at least 10 atmospheres gauge and'preferably shouldbe about 100 atmospheres gauge. l

According to the impro-ved process of the invention, about 70 to 80% ofthe deuterium content of natural hydrogen is removed and recoveredrather than the 20 to 30% removal which could `be attained by the priorprocess. A special advantageof the process according to the `inventionis that the quantity of :fresh natura1. hydrogen supplied for aparticular desired separation is substantially less than` that requiredwhen the process according to application Serial No; 531,980 withoutusing a 'stripping system is employed.

The yields obtained according to the invention can be Patented Mer. l,1.960A i employed with otherembodiments of the process described in myearlier application Serial No'. 531,980.

l. VInaV method' 'for the recovery of hydrogen enriched withdeuteriumemploying hydrogen containing deuterium as the' primary sourceof deuterium in an exchange concentrating system in which streams ofhydrogen and liquid" waterare passed countercurrently to each other indeuterium exchange relation in the presence of a catalyst promotings`uch exchange serially through two columns maintained 'at dilerenttemperatures, the hydrogen first passing through the column maintainedat the higher temperature andthen through the' column maintained at alower tempe'rature and the liquid water first passing through the columnmaintained at the lower temperature and then through the Vcolumnmaintained at the higher 'temperature, the'liquid water being passedthrough said columns being maintained in a closed cycle, and hydrogenenriched in deuterium is withdrawn from the hydrogen stream between thetwo columns and the hydrogen leaving the column maintained at the lowertemperature is depletedin deuterium,the stepswhich comprise passing allof the hydrogen leaving the column of said concentrating systemmaintained vat the lower temperature to the first of two columnsmaintained at different temperatures,` of astripping system in which`stripping system streams 'of the hydrogen and liquid Water areV passedcountercurrent to each other in deuterium exchanging relationship in thepresence of a catalyst promoting such exchange. serially through suchcolumns, the hydrogen from the ycolumn of the concentrating systemmaintained at the lower temperature first passing through the column ofthe stripping system maintained at the lower temperature and thenpassing through the column of said stripping system maintained at thehigher temperature and the liquid water first passing'through the columnof said stripping system maintained at the higher temperature and thenthrough title L'olumn of the stripping system maintained at the lowertemperature, theY liquid water being passed through the columns of saidstripping system being maintained in a closed cycle; withdrawing aportion of the hydrogen from the stream of hydrogen leaving the columnof the stripping system maintained at the lower temperature to provide ahydrogen which is still further depleted in deuterium, the remainingportion of said stream of hydrogen being passed through the column ofthe stripping system maintained at the higher temperature wherein itsdeuterium content is increased again and then recycling the hydrogenleaving the column ofthe stripping system maintained at thehighervtemperature to the column of the concentrating system maintainedat the higher temperature.

2. The process of claim 1 in which the water cycles of the concentratingand stripping systems are combined into one closed cycle in which thewater is irst passed through the column of the stripping systemmaintained at the higher temperature and then sequentially through thecolmn of-the stripping system maintained at the lower temperature, thecolumn of the concentrating system maintained at the lower temperatureand the column of the concentrating ysystem maintained at the highertemperature. I

3. .The processof claiml in which fresh hydrogen containing deuteriumemployed as thefprimary source of deuterium s introducedinto thehydrogen leaving the column of the stripping system maintained at thehigher temperature before it is introduced into the column of theconcehtratingsystem maintained at the higher temperaturerfff.

4. TheH process of claim 1 inwhich the corresponding columns. of theconcentrating andstripping systems are maintained at substantially thesame temperature and pressure.

Y: l'References Cited in the file of this patent UNITED STATES PATENTS2,787,526 'i vspr-.wack Apr. 2, 1957

1. IN A METHOD FOR THE RECOVERY OF HYDROGEN ENRICHED WITH DEUTERIUMEMPLOYING HYDROGEN CONTAINING DEUTERIUM AS THE PRIMARY SOURCE OFDEUTRIUM IN AN EXCHANGE CONCENTRATING SYSTEM IN WHICH STREAMS OFHYDROGEN AND LIQUID WATER ARE PASSED COUNTERCURRENTLY TO EACH OTHER INDEUTERIUM EXCHANGE RELATION IN THE PRESENCE OF A CATALYST PROMOTING SUCHEXCHANGE SERIALLY THROUGH TWO COLUMNS MAINTAINED AT DIFFERENTTEMPERATURES, THE HYDROGEN FIRST PASSING THROUGH THE COLUMN MAINTAINEDAT THE HIGHER TEMPERATURE AND THEN THROUGH THE COLUMN MAINTAINED AT ALOWER TEMPERATURE AND THE LIQUID WATER FIRST PASSING THROUGH THE COLUMNMAINTAINED AT THE LOWER TEMPERATURE THEN THROUGH THE COLUMN MAINTAINEDAT THE HIGHER TEMPERATURE, THE LIQUID WATER BEING PASSED THROUGH SAIDCOLUMNS BEING MAINTAINED IN A CLOSED CYCLE, AND HYDROGEN ENRICHED INDEUTERUIM IS WITHDRAWN FROM THE HYDROGEN STREAM BETWEEN THE TWO COLUMNSAND THE HYDROGEN LEAVING THE COLUMN MAINTAINED AT THE LOWER TEMPERATUREIS DEPLETED IN DEUTERUIM, THE STEPS WHICH COMPRISE PASSING ALL OF THEHYDROGEN LEAVING THE COLUMN OF SAID CONCENTRATING SYSTEM MAINTAINED ATTHE LOWER TEMPERATURE TO THE FIRST OF TWO COLUMNS MAINTAINED ATDIFFERENT TEMPERATURES OF A STRIPPING SYSTEM IN WHICH STRIPPING SYSTEMSTREAMS OF THE HYDROGEN AND LIQUID WATER ARE PASSED COUNTERCURRENT TOEACH OTHER IN DEUTERUIM EXCHANGING RELATIONSHIP IN THE PRESENCE OF ACATALYST PROMOTING SUCH EXCHANGE SERIALLY THROUGH SUCH COULMNS, THEHYDROGEN FROM THE COLUMN OF THE CONCENTRATION SYSTEM MAINTAINED TO THELOWER TEMPERATURE FIRST PASSING THROUGH THE COLUMN OF THE STRIPPINGSYSTEM MAINTAINED AT THE LOWER TEMPERATURE AND THEN PASSING THROUGH THECOLUMN OF SAID STRIPPING SYSTEM MAINTAINED AT THE HIGHER TEMPERATURE ANDTHE LIQUID WATER FIRST PASSING THROUGH THE COLUMN OF SAID STRIPPINGSYSTEM MAINTAINED AT THE HIGHER TEMPERATURE AND THEN THROUGH THE COLUMNOF THE STRIPPING SYSTEM MAINTAINED AT THE LOWER TEMPERATURE, THE LIQUIDWATER BEING PASSED THROUGH THE COLUMNS OF SAID STRIPPING SYSTEM BEINGMAINTAINED IN A CLOSED CYCLE, WITHDRAWING A PORTION OF THE HYDROGEN FROMTHE STREAM OF HYDROGEN LEAVING THE COLUMN OF THE STRIPPING SYSTEMMAINTAINED AT THE LOWER TEMPERATURE TO PROVIDE A HYDROGEN WHICH IS STILLFURTHER DEPLETED IN DEUTERIUM, THE REMAINING PORTION OF SAID STREAMHYDROGEN BEING PASSED THROUGH THE COLUMN OF THE STRIPPING SYSTEMMAINTAINED AT THE HIGHER TEMPERATURE WHEREIN ITS DEUTERIUM CONTENT ISINCREASED AGAIN AND THEN RECYCLING THE HYDROGEN LEAVING THE COLUMN OFTHE STRIPPING SYSYTEM MAINTAINED AT THE HIGHER TEMPERATURE TO THE COLUMNOF THE CONCENTRATING SYSTEM MAINTAINED AT THE HIGHER TEMPERATURE.